Soak the sultanas in 50ml/2fl oz of the cider until plump (about an hour, or you can do it overnight).
Preheat the oven at 180C/350F/Gas 4
Lightly grease an 18cm/7in diameter baking tin and dust it with flour.
In a bowl or food processor mix the butter and sugar. Next, add the beaten eggs, flours, baking powder, coriander and salt. Mix well.
Add the apple, the sultanas and their cider they soaked in, plus the remaining amount of cider to the cake mix, and stir to combine but do not beat.
Pour mixture into the cake tin and bake in the oven for 20-25 minutes till golden-brown and firm to touch. Remove from the oven and leave to cool.
For the cider syrup, in a saucepan bring the cider and granulated sugar to the boil, and when all the sugar has dissolved leave the syrup to cool.
Remove the cake from the tin and place on serving dish. Using a skewer prick the cake all over evenly. Slowly pour the cider syrup over the cake, then serve.